Cylinder-cap construction for compressors



H. E. THOMPSON CYLINDER CAP CONSTRUCTION FOR COMPRESSORS Filed Feb. 15. 1926 5 Sheets-Sheet l July 5, 1927. 1,634,633

H. E. THOMPSON CYLINDER CAP CONSTRUCTION FOR COMPRESSORS I5 Sheets-Sheet 2 Filed Feb. 15, 1926 INVEN TOR.

July 5, 1927. 1,634,633

, H. E. THOMPSON CYLINDER CAP CONSTRUCTION FOR COMPRESSORS 3 Sheets-Sheet 3 Filed Feb. 15. 1926 INVENTOR.

{M1, A TTORNEY.

construction of the Patented. July 5, 1927.

UNITED STATES PATENT OFFICE.

HARRY n; rnomrson,

or nnraorr, mrcrrrean,

CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

ASSIGNOR TO UNIVERSAL COOLER CYLINDER-can oonsrrwc'rron non conrrnnssons.

Application filed February 15, 1926. Serial No. 88,244.

This invention relates to improved cylinder cap construction for compressors espegreat diificulties in power the lossof the refrigerant.

refrigeration is due to leaks. It

is one of the objects of the present invention to provide a cylinder cap construction *of great thickness so as This not only cuts thecap distorting, of bolts necessary to form a bridge.

down the possibilities of but lessens the number to secure the cap to the cylinder block. Furthermore, this construe tion provides an unrestric the valve and thereby lessens ted chamber above the accumulation of heat instant ,to restricted and tortuous passage.

Another important improvement is the employ thick castings, this heat in the head and keeps accumulation of cylinder head partition metal. This rein. contrast tothe which ordinarily diminishes the the compressor working at cooler temperatures. It also eliminates prdjection of the piston the valve opening for the ing the clearance between and the top of,

drawings Fig. 1 pressor.

the cylinder. more fully explained hereinafter.

the necessity of a head to pass into purpose of lessenthe partition head This will' be In the is a vertical section of the com- Fig. 2 is a plan view of the same. Fig. 3 is a section on the line 3-3 of Fig. 2. Fig.

4 is a fragmentary section'taken at right angles to the showing of Fig. 1.

Fig. 5 is a section take of Fig. l.

n on the line 5-5 Fig. 6 is a section taken on the line 6-6 of Fig. 1.

Fig. 7 is a perspective view of the head,

and part of the valve cage.

It seems unnecessary to letter and call attention to the customary moving parts of a compressor such as the crank shaft, connecting rod, and piston rings on the cylin- The charge is circulates thr These are all clearly shown in the drawn in through oug-h the chamber the sides of the piston the piston pushes down,

immediately above the cylinder head,

the valve e rises from its seat and permits the charge head of the piston. When the piston movement is reversed this valve is thrown against its seat and the charge is compressed in the chamber above the pistonuntil the pressure accumulates sufiiciently to lift the light spring f that holds the valve 9 upon its seat. This valve can lift about a few thousandths of an inch when it encounters the resistance of theheavy spring h which bears against the shoulder g. This resists further opening of the valve unless an incompressible fluid accumulates between the piston head and the valve. This results in creating hydraulie pressure. This is heavy enough to lift the spring and blow out the accumulated lubricant, or other liquid. Clearance between .the partition head 2' and the head of thousandths of an relatively heavy partitions, or heads, from three-eighths to one-halfinch. As far as I am aware, these have always been castings and the valve 'caging is ordinarily in the form ot a boss, or ring, which is an integral part of such casting. Very often the springs that hold a valve on its seat abut against the inside of the cylinder cap. It is the obect of the present invention to provide not only an improved heavy bridging cap, but also provide an improved der head or partition." To this end I employ a piece of sheet metal stock of preferably one-eighth inch thickness. This does not require any machining to make it smooth enough to take the gaskets 9', nor to get an even clearance space above the end of the piston. y

In order to (provide a valve cage, studs k with reduce ends are riveted over in countersunk holes in the head. 'They are then welded in lace to secure them better and to seal the oint against all leakage. I shall not go into the details of valve cage construction, as that is a separate invention which is in my coending application, Serial No. 88,243, file February 15, 1926, for obviously it could be used with a different kind of cylinder head, such as a castin of considerable thickness.

lace of the usual flan ed cylinder cap in which the bolts are turns into the flange I utito pass through the valve.

sheet metal cylinflanges at all.

lize a heavy cylinder cap which really has no But in which the bolts, as shown in the Fig. 3, pass through substantially the entire side of the cylinder cap casting. This makes a heavy bridge, as it were, spanning the compression chamber above the cylinder head. This, I find very advantageous, for the lighter castings of the type having the usual bolt flanges very often distort slightly and produce leaks around the gasket, which cause no end of trouble. With that type of cylinder cap it is ordinarily thought necessary to use six bolts so as to counteract this bowing tendency of the flanges; by my cylinder cap, or bridge construction, tour bolts are all that are necessary. Furthermore, my bridge construction of the cap brings the bolt heads up to a point where they may be given more clearance from the body of the casting and it is possible to use wrenches on the bolt heads that can not be utilized when the bolts lie close in to the body of the cap.

it will also be apparent that the compres sion chamber m can be made somewhat larger in diameter with the bolts carried high, as shown in. Fig. 3, than will be possible where a flange construction is employed with the bolts the same distance apart between centers. It is desirable to get this compression chamber as large as possible so as to prevent the accumulation of heat in the compressor walls.

A similar advantage follows from the use of the relatively thin sheet metal. cylinder head, for of course, this member is directly in the path for hot gases, and where it is three or four times as large in cubical capacity it accumulates a proportionally greater amount of heat units to the detriment of the compressor operation. Furthermore, in these thick cast metal heads the port covered by the valve 9" being comparatively deep, it is found desirable to have a plug on the end oi the piston which is carried into this port to lessen the clearance space above the piston head to get the proper efiiciency and not leave part of the gases in the cylinder to reexpand after work has been done upon them, and to be rccompressed at each stroke. l have found that where this port is only onceighth inch deep that the amount of gas left in the cylinder at the end of each stroke is suficiently negligible so that this factor may be neglected and head or the piston. This is a desirable feature in building the compressors as it does away with the troublesome problem of very accurate machining of the cylinder heads and proper locating of the pistons in respect thereto, so that the plug will always be properly centralized with the port. This problem, by my construction, is entirely eliminated.

:dtill another feature is that the post con the plug omitted in the nose secured mtween menses struction, which I have described as being the design of the cage, is particularly ap propriate with this sheet metal cylinder head, and. the post construction permits an open valve cage. This materially increases the capacity of the compression chamber for ordinary sizes of cylinder caps, and thereby, more or less minimizes the problems due to the accumulation of heat.

The cylinder head is provided with the cooling fins a, which are designed for, and calculated to dissipate the heat accumulating in the cap.

What I claim is:

1. In a compressor the combination of a cylinder, a piston reciprocating in the cylinder, a cylinder cap, and a relatively thin cylinder head secured between the cap and the cylinder end and spaced from the cap, said head provided with a valve port which communicates directly with the space between the head and the cap, a valve mounted on the head for guarding the port, this port being of such limited depth, due to the thinness of the cylinder head, as to be practically a negligible factor in the clearance space left between the piston and the valve.

2. In a compressor the combination of a cylinder having a reciprocating piston therein, a cap for the cylinder which has thick side Wall'sv and which is secured to the cylinder by bolts passing through such side walls, a head for the cylinder consisting of a thin sheet of metal which is disposed between the cylinder body and the cap, this thin head being spaced from the top portion of the cap by reason of the thick side walls of the cap, valve mechanism disposed between the cap and the head and which is supported entirely by the said head and independent of the cap, including a valve which seats directly on the head, and the said head being provided with a port which is closable by the valve.

3. In a compressor, the combination of a cylinder having a reciprocating piston therein, a cap for the cylinder, means for securing the cap to the cylinder, a head for the cylinder consistin of a thin sheetof metal which is disposed oetween the cylinder and the cap. this'thin head being spaced from the top portion of the cap, valve mechanism disposed between the cap and the head which is sup? ported entirely by the said head and which is independent of the cap, and the said head being provided with a port which is closable by the valve, the clearance between the valve and the piston beingpractically negligible in the operation of the machine by reason of the thinness ofthe cylinder head.

i. In a compressor, the combination of a cylinder block, a piston reciprocating therein, a cap boltable to the end of the cylinder, sheet metal head or relatively smallthickthe cap and the end of the cylinder block and having an outlet port of relatively small depth, and valve cage posts supported by the thin head around said opening on the head and having each a hermetically sealed joint with said head.

5. In a compressor, the combination of a cylinder block, a piston. reciprocating therein, a cap boltable to the end of the cylinder, a sheet metal head of relatively small thickness secured between the cap and the end of the cylinder block and having an outlet port of relatively small depth and valve cage posts supported directly by the thin head about the outlet port and welded to the sheet metal head.

6. In a compressor, the combination of a cylinder block and a cap bolted thereto comprising a casting whose sides are comparasaid cap rising tion of its depth,

tively thick-the thickness constituting the major part of the depthof the casting to form bridging members between the top of the cap and the cylinderblock that tend to prevent the distortion or bowin of the cap.

7 In a compressor, the combination of a cylinder block, a cap, a cylinder head bolted between the cap and the endof the block, at its sides directly upwardly from the cylinder head for the major porbossof reduced diameter 'to complete the depth of the cap, and bolts passing through the upwardly rising portions thus formed at'the sides of the cap.

In testimony whereof I afiix' my signature.

HARRY E. THOMPSON.

and then forming a central- 

